Method for filling lamps



W. J. CAMERON.

METHOD FOR FILLING LAMPS. APPLICATION FILED sums. I9l9.

1,348,978. Patented m. 10, 1920.

flu/c7557 WZCZiam J Cameron Lamps, of which UNITED STATES.

WILLIAM J'. CAMERON, CHICAGO, ILLINOIS.

METHOD FOR FILLINGYLAMPS.

. Specification of Letters Yatent. Patented Aug '10, 1920,

; Application filediSepteniber 5, 1919. Serial $0,321,898.

To all whom, itmayconccm: 5 I

. Be it known that I, VViLLnmr LI. CAMERON, a subject of the King of Great Britain, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Methods for Filling the following is av specification. l i

f My invention relates to the manufacture of incandescent electric lamps, and more partlcularly to the type of lamp known as miniature surgical lamps,, such as that for which I obtained Letters Patent of the United States No. 1308,7 13, dated December 19, 1916. The lamp described in the aforesaid Letters Patent comprises, briefly, a very small incandescent bulb of approximately oneeighth inch diameter and onehalf inch in length that is positioned adjacent the inner closed clear 'lenticular end of an opaque or milk glass tube, and the circuit wires leading from this miniature bulb pass, respectively, inside and outside of an interior glass tube positioned within the aforesaid opaque tube. For the purpose offpreventing the rattling or shaking and breaking of the tube, and also to strengthen and re-inforce the structure and insulate the conductors, I have found it desirable to load the tube with a composition such as plaster of Paris. I v

It is with relation to this loading of the tubes that my present invention relates, and

comprises a method of filling the tubes in an expeditious and convenient manner, which will materially assist in ascertaining the proper amount of moisture to be supplied to the powdered plaster of Paris in order to secure the proper hardening or setting of the same. Heretofore, so.far as I am aware, it has been the custom to introduce the cementitious material into the lamp tubes in a plastic condition and'by hand, which methodis open to the serious objections arising from the fact that the plastic cementitious material is sticky, is hard to dispose in the proper position and that the rapid hardening, or setting thereof, even when the operation is performed quickly, prevents the uniform and dependable filling of the tubes.

My method of filling the lamps with the re-inforcing and insulating material consists in mounting the bodies or assembled structure, prior to the sealing of the open end with the usual threaded electric plug cap,

"in the bottom of a siftingpan, or similar structure in which powdered plaster of Paris is placed, and by means of a small tamping rod the individual tubes are tapped with this instrument interiorly until they have been compactly filled with the powdered plasterof Paris. The surplus powder is then removed from thesifting pan and a fibrous mat of felt or the like is pla'ced in the bottom, and the ma t,"sifting pan and tubes are inverted and placed in a pan of water or other liquid with which it is desired to moisten the plaster of Paris iIl'.tl16

tubes. By the action of capillary attraction the moistureis drawn upward into the tubes until all. of the powder therein has been moistened. For the purpose of observing the rate of rise of the moisturein the tubes (which latter are opaque), I employ a gage ;comprising a clear glass tube of. the same design as the lamp tube through which the rise of the moisture can be observed. At

,thedesired time the sifting pan is removed from the tray of water and the tubes containing the moistened plaster of Paris, which is now in a plastic state, are permitted to dry and set.

g In carrying out my invention, I prefer to employ an apparatus, similar to that disclosed in the accompanying drawlngs that form a part of this specification and which 'are diagrammatic-a1 for the purpose of ll.-

lustrating schematically a preferred form of structure. In these drawings Figure 1 1s a view partly in section of a fragmental portion of a sifting pan show-.

ing a tamping tool in the process of tamping the powder into a tube.

Fig. 2 is a View of the succeeding step showing the sifting pan provided with the fibrous mat and inverted in a tray of water.

In. the drawings, 5 indicates a shallow tray, preferal'zly, of metal, the bottom whereof is provided with a plurality of openings,

6 formed by stamping several rows of cylindrical stubs 7 out of the metal. These stubs are each provided with a small tubular gasket 8, preferably, of rubber tubing or the like, the diameter of which is slightly less than the outside diameter of the glass tube ,9 of the lamp which is inserted therein.

Under ordinary conditions the friction between the parts is sufficient to hold tubes 9 in position, but to insure against accident, I prefer to employ small spring clips 10 that project below stubs 7 and engage the annular external ribs 11 upon the adjacent end of the lamp tube. After the lamptubes have been positioned' in stubs 7 ,the sifting tray 5 receives a quantity of plaster of Paris 12 in powdered form and a small tamper 13, or similar tool, is employed to tamp them and pack the powdered plaster of Paris in the interior and outer tubes of each lamp. After all of the tubes have been packed with plaster of Paris, the surplus is removed from sifting tray 5 and a suitable mat of felt 14: or other fibrous material is placed therein to cover all of the openings 6, and the open ends of the lamp tubes. The structure is now inverted, as seenin Fig. 2, and placed ina pan 15 containing water or other liquid with which it is desired to :moisten the powder in the tubes. The action of capillary attraction raises the water and moistens the powder in the tubes, and after the moisture has "risen in the tubes. the desired distance, the

sifting tray is removed from the water pan and the plaster mass .is now permitted to dry and set in the lamp tubes.

As before mentioned the lamp tubes are of an opaque or'milk glass with the exceptionof their lenticular ends, and in order to observe the time taken for the water to rise inthe lamp tubes, I have provided a lamp tube 16 of clear or transparent glass that is fitted into one of the stubs of the sifting tray and loaded with the powdered material so that the rise of the moisture may be observed therein and the permeation of the material controlled. It will be understood that the elements of the lamp are as sembled in their desired relation with each other prior to being mounted in the sitting tray, and the central or dividing tube 17 is positioned within the exterior opaque tube 9 and the powdered plaster of Paris is tamped into this inner tube 17 as well as into the space between; the same and tube 9 surrounding the same.

1. The method of loading tubular bodies with cementitious filler consisting of mounting the bodies pendent in a sitting tray; introducing into the tray cementitious material in a dry, finely divided condition; agitating the cementitious .material to fill the bodies, and inverting the tray in a liquid, whereby the liquid permeates the material in said tubes capillarity and the rate and extent of such permeation may be observed and controlled.

2. The method of loading tubular bodies with a cementitious filler, consisting of mounting the bodies pendent in a sitting tray; introducing into the tray cementitious material in a dry, finely divided condition; agitating the cementitious material to fill the bodies covering the open ends of said tubes with a porous mat, andinverting the tray in a liquid, whereby the liquid permeates the material in said tubes by capillarity and the rate and extent of such permeation may be observed and controlled.

3. An elongated tubular electric lamp wherein the conductors have been surrounded with a cementitious material in a dry, finely divided condition andpermeated with a liquid by capillarity to cause a hardening of said material. I

Signed at Chicago county of Cook and State of Illinoisthis 2nd day of September VILLIAM J. CAMERON. \Vitnesses E. K. LUNDY, Jr., FLORENCE MITCHELL. 

